Chairs with reclining backs have been popular for more than one hundred years. Typical chairs of this type normally used a pivotal connection of the back support to an immovable part of the chair to allow for selective movement of the back support at an angle relative to the rest of the chair. In some cases, the pivotal connection was accomplished by the use of links and linkage systems as shown in the patents which accompany the enclosed information disclosure statement.
In each of the prior patents, a chair is disclosed with a reclinable back support which is connected by linkages to the chair base, arm supports, or seat supports. As the back support reclines, the vertical displacement between the top edge and the support surface lessens and the angle between the seat and back support gradually increases. This causes the vertical eye level of a user seated in the chair to be lowered which effectively changes the field of vision and often requires adjustments to be made to the surroundings.
Some of the prior art designers recognized the problems associated with eye level change and designed chairs whose seat supports also has mechanisms connected between the seat and the chair base. This allowed the user to selectively raise and lower the seat in response to eye level change caused by reclining the back support.
The prior art chairs identified above also did not address the mechanical balance of the chair to allow for the chair's tilt action tension to automatically adjust to all variations of a user's weight. Typically, when one of the prior chairs was shifted into the reclined position it was unbalanced until it reached its full reclined position or it was necessary to lock the chair in various tilting degrees. The unbalanced design of these chairs is annoying for users of different body weight especially in offices, vehicles, and theaters where chairs are used by so many different users daily.